Compass

ABSTRACT

The compass according to the invention comprises a compass top and two compass legs (1,2) mounted rotatably in the compass top, the compass top comprising two top-halves (3,4). Provided in each compass-top half is a bearing pivot (19) for respectively bearing a compass leg, as well as a counter-core (20) which, in the assembled state, engages in the bearing pivot of the corresponding compass-top half. A permanent and even radial frictional clamping is thus produced. At the same time, the counter-cores bring about a limitation to the opening of the compass due to corresponding in the compass legs.

BACKGROUND OF THE INVENTION

So-called single-journal compasses are known from DE-C 29 11 015 andGB-C 1,170,243. In these single-journal compasses having a compass topin which the compass legs rotate together about a pivot formed as ascrew, the screw causes axial frictional clamping at the apex of theconnected compass legs, in that, in interaction with a counter-nut orwith a counter-thread, the friction surfaces of the legs are squeezedtogether.

Both the previously known compasses require the use of relativelyexpensive metal screws. Additionally, the two previously known compassesdo not have straight guiding of the compass top; the compass top thusassumes different angles relative to the drawing plane depending on theangle of opening of the compass legs. This lack of straight guidingmakes use of the compass difficult since the compass top constantly hasto be positioned during use.

A drawing instrument, in particular a drawing compass or dividers orcallipers, is known from DE-C 27 33 978. In this case, an axialfrictional clamping is likewise produced by a large-area leg top and bya screw with a counter-nut. Furthermore, an additional punching platemade of steel is provided for the straight guiding of the compass top.

The three parts mentioned, screw, counter-nut and punching plate, makethe compass expensive and lead to complicated assembly of the individualparts of the compass. Apart from the three parts mentioned which consistof metal, the compass legs must also be made of metal since the compasslegs are of narrow design; the use of plastic material for the compasslegs is virtually ruled out since these would bend in a non-permissiblemanner during use.

A compass is already known from DE-C 25 23 046, in which two tighteningscrews each form a pivot for each of the two compass arms.

Compasses, whose top and legs are attached using a screw, are known fromthe following publications: DE-A 1411830, DE-C 243002, DD 280072, DE-A4201854, DE-U 1863371, U.S. Pat. No. 4,858,32E, DE-A 2922999.

The use of screws for attaching the compass leg and the compass topfirstly entails the disadvantage of the relatively high cost of thescrews. Moreover, when using screws, the axial frictional clamping theycause can only be adjusted or readjusted with difficulty. Moreover,there is the risk that compasses with self-tapping screws without acounter-nut become overturned, thus losing the requires frictionalclamping and becoming unusable.

SUMMARY OF THE INVENTION

Setting out from this prior art, the invention is based on the technicalproblem of providing a compass of simple construction which can be bothmanufactured and operated in a simple manner.

The compass according to the invention can be manufactured without theuse of screws and counter-nuts or counter-threads. Readjustment of thefrictional clamping during use of the compass is not required owing toits construction.

In particular, in the compass according to the invention, an essentiallyradial frictional clamping is formed between the compass legs and thecompass top, while an axial component of the frictional clamping formedis of only subsidiary importance

In particular, the bearing pivots of the compass top ace of slightlyconical design so that, when the compass legs are mounted on the compasstop, the bearing pivots engage with slight press-fitting in thecorresponding bores of the compass legs. The conical design of thebearing pivots also facilitates the manufacture of the compass top bythe injection moulding method.

According to the invention, (first) spreading cores can be introducedinto the counter-cores which engage in the bearing pivots andadditionally spread the latter apart in the end position of the bearingpivots in the counter-cores so that the connection is non-releasable.

A further advantageous embodiment is characterized in that, in theregion of the compass-top half, the width of each compass leg is suchthat it essentially corresponds to the width of the compass-top half.Bending of the compass legs is avoided or reduced due to this relativelywide design of the legs.

According to a further advantageous embodiment, the compass leg has, inthe region of the respective counter-core, an opening which is shapedsuch that it defines the angular adjustment of the compass leg.

According to a further advantageous embodiment, each compass leg has atoothing in the region of an opening which receives the bearing pivot,the teeth of the two compass legs meshing with one another and, in thisway, guide the compass top in a straight manner.

According to a further advantageous embodiment of the invention,corresponding centering elements are provided in the compass-top halfand in the compass legs. As a result, lateral bending which occureduring loading of the leg is absorbed.

According to a further advantageous embodiment of the invention, thetightening tongs which receive a compass point or a writing element areopened laterally so that the compass point and the writing element canbe introduced into the tightening tongs or removed from the tighteningtongs in a simple manner.

In this regard, a tubular piece can also be provided, which is receivedby the tightening tongs and which, in turn, receives a writing elementor a point. This considerably extends the range of application of thecompass; the compass can also be used as dividers or callipers.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are now described in greaterdetail with reference to the following drawings, in which:

FIG. 1 shows the front view of an exemplary embodiment of a compass inthe closed state according to the present invention;

FIG. 2 shows the side view of the same compass;

FIG. 3 shows a horizontal section along the line A--A in FIG. 1;

FIG. 4 shows a front view of the same compass in the maxim opened state;

FIG. 5 shows a view of the outer side of a compass leg;

FIG. 6 shows a side view with a partial section along the line A--A inFIG. 7;

FIG. 7 shows a view of the inner side of the compass leg according toFIG. 5;

FIG. 8 shows a horizontal longitudinal section along the line B--B inFIG. 5;

FIG. 9 shows a partial section along the line C--C in FIG. 5;

FIG. 10 shows a view of an insertion part which may be a constituentpart of a compass leg according to FIG. 5;

FIG. 11 shows the side view of the insertion part according to FIG. 10;

FIG. 12 shows a cross-section along the line D--D in FIG. 10;

FIG. 13 shows a section along the line B--B of the compass-top halvesshown in FIG. 14 and the upper region of the compass legs;

FIG. 14 shows a cross-section along the line A--A in FIG. 13;

FIG. 15 shows a horizontal section along the line C--C in FIG. 13;

FIG. 16 shows a horizontal section along the line D--D in FIG. 13;

FIG. 17 shows a section similar to FIG. 13, the compass legs being shownin the maximum opened state;

FIG. 18 shows an extract enlargement of a detail of FIG. 14;

FIG. 19 shows a perspective view which shows the complete assembly ofthe two compass-top halves with the compass legs, a first leg alreadyhaving been fitted onto a compass-top half, and another leg being shownin a position prior to its assembly on the other compass-top half;

FIG. 20 shows a partial section of tightening tongs with a graphiteinsert of a compass leg according to the present invention;

FIG. 21 shows a section along the line A--A in FIG. 20;

FIG. 22 shows a partial section of the tightening tongs with a compasspoint of a compass leg according to the present invention;

FIG. 23 shows a section along the line B--B in FIG. 22;

FIG. 24 shows a partial section of tightening tongs of a compass legwith a compass point held in a tubular piece according to the presentinvention; and

FIG. 25 shows a section along the line C--C in FIG. 24.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As can be seen from FIGS. 1 to 4, the compass comprises the followingmain constituent parts: a compass top which is composed of two halves 3and 4, and a first and a second compass leg 1 and 2 which are bothattached in the compass top and are mounted rotatably. A grippingportion 5 is formed on the compass top. The legs are made, inparticular, of plastic material and can be reinforced with a profiledinsertion part 6 made of steel sheet.

Located at the lower end of the first compass leg 1, that is to say inthe region of the foot, are tightening tongs 25 (FIGS. 5, 6, 7 and 9 )and a threaded sleeve 7 (FIGS. 1, 2 ), which together clamp, forexample, a graphite insert 8 or another type of writing element such as,for example, a ball-point pen insert, an ink pen or felt pen, etc.Likewise located at the lower end of the second compass leg 2 aretightening tongs 29 (FIG. 22) and a threaded sleeve 9, which togetherhold, for example, a compass point 10.

FIG. 19 shows the design of the compass-top halves 3 and 4 and of thetwo compass legs 1 and 2 in their top region as well as their assembly.The compass top comprises two compass-top halves 3 and 4. A bearingpivot 19', 19 (concealed in FIG. 19) and a counter-core 20', 20 areprovided in each compass-top half 3, 4.

Provision may be made for either a bearing pivot or a counter-core to bepresent in each of the two compass-top halves. With the compass legswhich are arranged on the same bearing pivot, the compass-top halvesdesigned in this manner form a single-journal compass. These compasslegs do not have teeth 16, 16' which are described below in conjunctionwith the compass legs of a two-journal compass.

The bearing pivots 19', 19 engage in the counter-cores 20', 20 therespective other compass leg, preferably with press-fitting, and, in theassembled state, form a virtually non-releasably connection.

The two legs 1 and 2 are arranged relative to one another as shown inFIG. 15. In this case, they come into engagement with their toothing 16and 16'. The toothing, which has yet to be described serves for thestraight guiding of the compass top.

The compass-top halves 3 and 4 are mutually fitted together forassembly. In this case, the bearing pivot 19 of the compass-top half 4is fitted through an opening (bore) 13 in the upper part the leg 1 andpressed onto the counter-core 20' of the opposite compass-top half 3. Inthis position, the counter-core 20 of the compass-top half 4 is passedthrough an opening 14 in the leg (FIG. 19). This opening is shaped suchthat it defines the angular adjustment of the respective leg.

The bearing pivot 19' of the compass-top half 3 is likewise fittedthrough the bore 13' in the upper section of the leg 2 and pressed ontothe counter-core 20 of the opposite compass-top hall 4. TV counter-core20' is passed through an opening 14' in the leg 2. An additional (first)spreading core 21 (FIG. 18), which is locate in the internal bore of thebearing pivot 19 of the compass-top half 4, enters into the counter-core20' of the compass-top half and spreads it apart to form anon-releasable connection of the two compass-top halves 3 and 4. Afurther (first) spreading core 21' in the bearing pivot 19' also bringsabout the connection of the two compass-top halves in the same manner.Instead of the spreading cores or even in addition to the spreadingcores, provision may be made for the counter-core and bearing pivot tobe bonded or welded to one another, for example, thus forming anon-releasable connection.

Owing to the design of the bearing pivot, the counter-core and thespreading core, as described, the two legs 1 and 2 are held so as to bemovable without play between the two compass-top halves 3 and 4. Anaxial frictional clamping is produced between the outer surfaces of thelegs and the inner surfaces of the compass-top halves, the absence ofplay being important for reducing the bending of the legs in the workingposition. The axial frictional clamping occurring, however, is ofsecondary importance for the function of the compass according to theinvention. Of primary importance in the compass according to theinvention is a radial frictional clamping, as will also be describedbelow.

The inner and outer surfaces of the bearing pivots 19, 19', the bores13, 13' in the legs 1 and 2 and the counter-cores 20, 20' are ofslightly conical design. During manufacture, this allows, on the onehand, reliable demoulding of the parts from the injection mould and, onthe other hand, assembly which is easy to automate, there being noproblem concerning the tolerances required for injection moulding toproduce the different diameters of the plug connection. Furthermore, bythis design of the said parts, press-fitting between the bearing pivotand the counter-core and slight press-fitting between the bearing pivotand the compass leg are formed.

In the case of the press-fitting between the bearing pivot 19 and thecounter-core 20', a first tension is built up between the inside wall ofthe bearing pivot 19 and the outside wall of the counter-core 20'(depicted by the pair of arrows on the right in FIG. 18) and a secondtension is built up between the outside wall of the spreading core 21and the inside wall of the counter-core 20' (depicted by the pair ofarrows on the left in FIG. 18). The two tensions are superimposed andact on the wall of the bore 13 of the leg 1. On these surfaces, aparticularly permanent and even radial frictional clamping is thusproduced, which guarantees secure working an all angular settings of thecompass. In the compass according to the invention, a permanent, radialfrictional clamping is thus formed by elements which, on the one hand,connect the compass-top halves to one another and which, on the otherhand, hold the compass legs in the compass-top halves.

When preferably using self-lubricating plastic materials for thecompass-top halves, at least for the outside walls of the bearing pivotson the one hand and/or the inside wall of the bores 13, 13' of thecompass legs on the other hand, premature wear is avoided and goodhandling and a long service life are thus guaranteed.

An exemplary embodiment of the compass leg 1 with a plastic-sheathed,for example, metal insertion part 6 is illustrated, in particular, inFIGS. 5 to 12. The insertion part 6 (FIGS. 10 to 12) is profiled(profile 11) and thus gives the plastic legs a particular strength.Insertion parts 6 are provided, in particular, in the region of the legtop and/or in the region between the leg top and the foot. Connectionholes 12 in the insertion part 6 receive the plastic material and thusadditionally increase the rigidity of the legs.

The bore 13 in the compass leg 1, as already described, is provided forreceiving a bearing pivot 19, while an opening 14 which is, for example,partially circular (whose associated centre-point form the bearing pivot19) serves to guide a counter-core 20 and thus defines the angularadjustment of the leg. The inside wall of the bore 13 can be of conicaldesign, as already described.

FIG. 17 shows that, in the case of maximum opening of the compass, thecounter-core 20 strikes against the opening 14 and thus prevents furtheropening of the leg 1 and, in interaction with the teeth 16, 16', also ofthe leg 2. A secure working range of the compass is guaranteed by thissimple and, at the same time, sturdy arrangement.

The compass legs 1 and 2 illustrated in the figures have, on the innerside and outer side, a plurality of cutouts 15 which are caused by coresof the injection moulds. These cores hold the insertion part 6 centrallyduring sheathing and also allow it to become partially visible so thatthe visual effect of the metal remains intact. On the inner side of theupper end, the leg 1 is fitted with a projecting toothing 16 (FIG. 13)and, on the outer side of the upper end, with a centring projection 17(FIG. 14) which engages in a corresponding depression 18 (FIG. 18) inthe top-half 4 (FIGS. 13 to 18).

The centring projection 17 of the leg 1, which projection is passed intothe corresponding depression 18 of the compass-top half 4, preventsbending of the bearing pivot 19 and of the corresponding counter-core20' since lateral bending of the centring projection 17 occurring duringloading of the leg 1 is absorbed. It is true in general thatcorresponding centring elements are provided in the compass-top halvesand in the compass legs, which elements prevent bending of the legs. Inparticular, the centring elements in the compass-top halves are designedas depressions 18, 18' and the centring elements in the compass legs aredesigned as centring projections 17, 17'. The depressions and centringprojections are of circular design.

In order to avoid or reduce bending of the compass legs, the legs aredesigned to be relatively wide, it being possible for the width of thelegs to correspond in their upper section to the width of the compasstop.

In order to reinforce the connection of the two compass-top halves, twofurther attachments are provided, as illustrated in FIGS. 13, 14, 16 and19. These are, for example, journals, in particular hollow journals 22,22' and receiving elements 23, 23' for the journals 22, 22' (FIGS. 16,19). The hollow journal 22' of the compass-top half 3 is pressed intothe corresponding receiving element (bore) 23 of the compass-top half 4.Additionally, a second spreading core 24 of the compass-top half 4 isinserted into the inner bore of the hollow journal 22', the secondspreading core 24 spreading the journal 22' apart to form anon-releasable connection. The journal 22, a bore 23' and a secondspreading core 24' interact in an analogous manner (FIG. 16).

As illustrated in FIGS. 5 to 9, tightening tongs 25 with a slot 26 forreceiving, for example, a graphite insert 8 are located in the region ofthe foot, that is to say at the lower end of the leg 1. The tighteningtongs 25 are arranged so as to be slightly sloping relative to the leg.This results in a setting angle 27 of about 53° at the maximum openingof the compass. In total, reliable working throughout the entire workingrange of the compass is guaranteed by this arrangement (FIG. 4).

FIGS. 20, 21 show that the tightening tongs 25 are open on one side dueto a longitudinal groove 28. A section of the open longitudinal grooveis illustrated in FIG. 9. In conduction with the threaded sleeve 7which, when screwed closed, closes the tightening tongs 25 which have aslot 26, the graphite insert 8 is clamped. The lateral opening in thetightening tongs has the advantage that the user of the compass has easyaccess, for example when exchanging a broken graphite insert. This isnot the case in the otherwise customary tightening tongs which haveblind bores and are closed continuously at the side. The front bore(=bore which is disposed downwards during use of the compass) of thethreaded sleeve 7 centres the graphite insert when the tightening tongs25 are closed. The opening width of the longitudinal groove 28 is atleast equal to the outside diameter of the graphite insert 8 or thewriting element.

The tightening tongs 29 for the compass point 10 shown in FIGS. 22 and23 likewise has an open longitudinal groove 30 and a slot 31 which,together with the threaded sleeve 9, clamps the compass point 10 whenscrewed closed and holds it centrally.

Moreover, the arrangement of the open longitudinal grooves 28 and 30also has the important advantage, in terms of manufacture, of aconsiderable simplification of the injection mould for the legs and 2since no complicated lateral slide constructions are necessary.

Owing to the fact that, as is otherwise customary, the compass pointdoes not have to be inserted into the extension of the compass leg fromthe front, but can be inserted laterally via the open longitudinalgroove, it is possible to use a commercially available pin with a headas the compass point. The arrangement of the tightening tongs and thethreaded sleeve provided according to the invention allows a shortprojection over the tip both of the graphite insert and of the compasspoint. In the case of the graphite insert, this leads to a lesser riskof breakage and, in the case of the compass point, a considerablyreduced risk of injury.

The arrangements of the tightening tongs illustrated in FIGS. 24 and 25is identical to that shown in FIGS. 20 and 21. Instead of the graphiteinsert, a pin with a tubular piece 32 is used, the tubular piece havingthe same outside diameter as the graphite insert. The compass can thusalso be used as dividers or callipers.

Provision may also be made for the tightening tongs to have an insidediameter which is larger than the outside diameter of customary graphiteinserts or customary compass points. The inside diameter of thetightening tongs can be designed for tubular pieces of larger outsidediameter, the said tubular pieces receiving compass tips or writingelements (graphite inserts, ballpoint pen inserts, etc.).

The legs can be produced, for example, from a metal alloy based on zinc(e.g. dye-casting zinc alloy "Zamak") which is suitable for dye casting.

The compass according to the invention can also be designed withidentical teeth and tightening tongs on both legs, thus enabling theproduction process to be less expensive. In the case of an identicaldesign of the legs, the two bearing pivots in the compass-top halves areoffset in such a way that two sets of teeth engage in one another.

    ______________________________________                                        Items:                                                                        ______________________________________                                         1       First leg                                                               2 Second leg                                                                  3 First compass-top half                                                      4 Second compass-top half                                                     5 Gripping portion on compass top                                             6 Insertion part                                                              7 Threaded sleeve in leg 1                                                    8 Graphite insert/writing element                                             9 Threaded sleeve in leg 2                                                   10 Compass point                                                              11 Profile                                                                    12 Connection holes                                                           13, 13' First opening                                                         14, 14' Second opening                                                        15 Cutouts                                                                    16, 16' Toothing                                                              17, 17' Centring projection                                                   18, 18' Depression                                                            19, 19' Bearing pivot                                                         20, 20' Counter-core                                                          21, 21' First spreading core                                                  22, 22' Hollow journal                                                        23, 23' Bore                                                                  24, 24' Second spreading core                                                 25 Tightening tongs for graphite insert/writing element                       26 Slot in leg 1                                                              27 Setting angle                                                              28 Longitudinal groove in leg 1                                               29 Tightening tongs for compass point                                         30 Longitudinal groove in leg 2                                               31 Slot in leg 2                                                              32 Tubular piece                                                            ______________________________________                                    

I claim:
 1. A compass comprising: a compass top portion with a firstcompass top half and a second compass top half; two compass legs mountedrotatably in said compass top portion; a bearing pivot in said firstcompass top half for supporting said compass legs; a counter-core insaid second compass top half and engaging in an assembled state in saidbearing pivot, said counter-core being connected non-releasably to saidbearing pivot by a spreading core, said compass being free of fasteningelements.
 2. A compass as defined in claim 1, wherein said two compasslegs are comprised of plastic material and have at least one metalmember in a region of a top portion of the legs and in a region betweena top portion and a foot portion of the legs.
 3. A compass as defined inclaim 2, wherein said metal member comprises an insertion part.
 4. Acompass as defined in claim 3, wherein said insertion part hasthrough-holes for receiving said plastic material.
 5. A compass asdefined in claim 1, wherein said first and second compass top halvesform a single-journal compass.
 6. A compass as defined in claim 5,wherein said bearing pivot and said counter-core have conically-shapedsurfaces.
 7. A compass comprising: a compass top portion with a firstcompass top half and a second compass top half; two compass legs mountedrotatably in said compass top portion; a first bearing pivot in saidfirst compass top half, and a second bearing pivot in said secondcompass top half; a first counter-core in said first compass top half, asecond counter-core in said second compass top half; said firstcounter-core engaging in an assembled state in said second bearing pivotof said second compass top half; first connecting means for connectingsaid first counter-core non-releasably to said second bearing pivot;said second counter-core engaging in an assembled state in said firstbearing pivot of said first compass top half; second connecting meansfor connecting said second counter-core non-releasably to said firstbearing pivot.
 8. A compass as defined in claim 7, wherein said firstand said second connecting means are formed by a spreading core in saidfirst and second counter-cores.
 9. A compass as defined in claim 8,including a second spreading core in an internal bore of a journal ineach compass top half.
 10. A compass as defined in claim 7, wherein saidcounter-cores and said bearing pivots are correspondingly secured to oneanother.
 11. A compass as defined in claim 7, wherein said bearingpivots have adjacent walls, said adjacent walls and the respectivecounter-cores having correspondingly conical surfaces.
 12. A compass asdefined in claim 7, wherein in a region of said compass top halves eachof said compass legs have a width corresponding to a width of saidcompass top halves.
 13. A compass as defined in claim 12, wherein eachcompass leg has an opening in the region of the respective counter-core,said opening having a shape defining an angular adjustment of thecompass leg.
 14. A compass as defined in claim 7, wherein each of saidtwo compass legs has toothing means in a region of an opening receivingthe respective bearing pivot, the toothing means on said two legsmeshing with one another.
 15. A compass as defined in claim 7, whereineach of said compass legs has an opening receiving the respectivebearing pivot, said opening having an inside wall of self-lubricatingplastic material, said bearing pivot having an outside wall ofself-lubricating plastic material in a region of said opening.
 16. Acompass as defined in claim 7, including centering elements in saidcompass top halves and in said compass legs.
 17. A compass as defined inclaim 16, wherein said compass top halves have a depression; and arespective centering projection in each of said compass legs.
 18. Acompass as defined in claim 7, wherein said compass top halves haveattachments.
 19. A compass as defined in claim 18, wherein each compasstop half has a journal with a receiving element for the respective othercompass top half.
 20. A compass as defined in claim 7, includingtightening tongs on said legs and having a longitudinal groove forreceiving a compass point or a writing element in a region of the footof said legs, said groove having an opening width equal to at least anoutside diameter of the compass point or the writing element.
 21. Acompass as defined in claim 20, wherein said compass point is formed bya pin.
 22. A compass as defined in claim 20, including a tubular memberin form of a receptacle in a foot of the compass, said tubular memberhaving an outside diameter substantially equal to an outside diameter ofthe writing element or the-compass point.
 23. A compass as defined inclaim 22, wherein said tubular member receives the compass point or thewriting element.
 24. A compass as defined in claim 23, wherein thecompass point is formed by a pin.